The present invention relates to a device for the determination of the vibrations occurring at the internals of a reactor pressure vessel by the use of a deflection detector connected to the internals.
The lifetime of deflection detectors inside a reactor pressure vessel is not very long because of the high temperatures, radioactivity levels, and pressures prevailing there. For this reason, their use over the entire operating period of a reactor system of about forty years is not possible.
A devie is known from German Patent Application No. 2,532,247 in which the vibrations are determined with a seismic deflection detector. The deflection detector for this purpose is bolted to the structural components to be monitored. In the replacement or repair of the deflection detector during the annual fuel assembly replacement taking place with the reactor pressure vessel opened, a substantial radiation exposure of the operating personnel must be expected when used in the area of the reactor pressure vessel internals. Furthermore, installation and removal with pole-like tools to cross the distance provided by a shielding layer of water is involved and time-consuming.
It is therefore the purpose of this invention to describe a device of the type mentioned initially by the use of which a direct vibration measurement and the installation and removal of the deflection detector with the reactor pressure vessel closed is possible, while avoiding the indicated drawbacks.